Field of the Invention
The invention relates to a process and a device for obtaining a sample from the atmosphere in a closed gastight vessel, preferably from the reactor safety vessel of a nuclear power station, wherein the sample is introduced into a sample-taking container and constituents of the sample which are soluble and/or condensable in a transport or vehicle fluid are discharged from the vessel together with the transport fluid and gaseous constituents of the sample. Such a process and a device suitable for carrying out the process are known from German Published, Non-Prosecuted Application DE 39 32 712 A1, corresponding to Published European Application No. 0 419 994 A1 and to U.S. application Ser. No. 07/590,151, filed Sep. 28, 1990, now abandoned.
Gastight vessels are frequently used for enclosing installations in which substances that must not pass into the environment of the vessel are reacted. Such vessels, which are also known as containments, are normally accessible while the installation enclosed in them is working correctly, and at the same time they also permit problem-free monitoring of the atmosphere contained in them. However, in the event of faults, the vessels are hermetically sealed in accordance with regulations, so that difficulties are encountered in obtaining samples from the outside which are representative of the atmosphere.
When taking samples, the different states of the atmosphere, such as "dry" and "moist", as well as the behavior of the substances in gas or vapor form and of air-borne solid and liquid aerosols are of considerable importance. In particular, effects such as depositions of condensing vapors or large aerosols (&gt;1 .mu.m) upstream (in the direction of flow) of a sample taking device may result in a highly erroneous assessment of the composition and of a radioactive contamination of the atmosphere.
In the device referred to above, sample taking fittings which are connected serially are provided in the run of a pipe loop, with each of them being able to be operated by means of a pneumatic or hydraulic line. Two penetrations of the wall of the vessel are then needed for the pipe loop in addition to one such penetration for each pneumatic or hydraulic line. Since the strength and tightness of the vessel must not be impaired thereby, it entails an expense which is not inconsiderable. Furthermore, the mechanically active sample taking fittings must also remain capable of operating under and after accident conditions, such as with temperatures above 500.degree. C. and extreme radiation loads of over 10 KGy/h, so that stringent demands on materials, particularly for moving parts, have to be met.